C# Create Visual Studio web app that creates an invoice

HiI am new to the Xero APIIs there a step by step guide to build a C# project where a user can create a simple Xero invoiceat the click of a buttonI have gone through the following video and I am able to connect to my new application in Xero but I am still confused about where I would put code to create an invoicehttps://developer.xero.com/documentation/libraries/using-the-xero-api-with-c